Electronic Device LED Placement for Fingerprint Imaging
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Solution Overview
Problem
Existing electronic devices that authenticate biometric features, such as fingerprints, face challenges in efficiently irradiating a part of a living body with light due to the placement of light emitting diodes (LEDs) on side surfaces of a light guide plate, leading to difficulties in alignment and increased costs from additional parts required to prevent light leakage.
Innovation Solution
The solution involves arranging LEDs around the imaging unit and using a refractive part with microprisms to guide light efficiently to the contact region, eliminating the need for a cover to prevent light leakage and reducing the number of parts, thus allowing for a more cost-effective and flexible design.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If LEDs are placed on side surfaces of light guide plate, then light can be emitted to contact region, but alignment becomes difficult and additional parts are needed to prevent light leakage
Solution Approach 1:
The patent inverts the conventional arrangement by placing LEDs around the imaging unit rather than on side surfaces of the light guide plate. This inversion eliminates the need for cover members to prevent light leakage and simplifies the overall structure, directly resolving the technical contradiction between ease of manufacture and device complexity
Solution Approach 2:
The patent extracts and removes the cover member component that was previously necessary to prevent light leakage from side-placed LEDs. By taking out this unnecessary part through the inverted LED arrangement, the device complexity is reduced while maintaining manufacturing ease
2Reliability
If LEDs are placed on side surfaces of light guide plate, then light emission is achieved, but additional cover parts are required to prevent light leakage
Solution Approach 1:
By inverting the LED placement from side surfaces to positions around the imaging unit, the patent achieves reliable light guidance to the contact region without requiring additional cover parts. The inverted arrangement naturally directs light where needed while eliminating the need for light-leakage prevention components
3Illumination intensity
If conventional LED arrangement is used, then light emission is achieved, but cost increases due to additional parts
Solution Approach 1:
The inverted LED arrangement around the imaging unit maintains effective light emission to the contact region while eliminating the need for expensive cover members. This design reduction directly lowers manufacturing costs while preserving illumination efficiency
Solution Approach 2:
The patent merges the LED arrangement with the imaging unit structure, allowing LEDs to be positioned around the imaging unit in an integrated configuration. This merging eliminates separate cover components and reduces overall manufacturing cost while maintaining light emission effectiveness
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This arrangement allows for efficient light guidance to the contact region, reducing costs and complexity, while enabling high-quality fingerprint imaging without the need for additional components to prevent light leakage, thereby enhancing the authentication process.
Implementation Method 1
a refractive part 110 is provided which is interposed at least between the LED 106 and the light guide plate 103 and refracts the light emitted from the LED 106 to guide the light to the contact region AR of the fingerprint
Implementation Method 2
The light guide plate 103, the image sensor 105A, and four light emitting diodes (LEDs) 106 (106A to 106D) are arranged inside the body part 30. A refractive part 110 is provided which is interposed at least between the LED 106 and the light guide plate 103 and refracts the light emitted from the LED 106 to guide the light to the contact region AR of the fingerprint
Data Source
Figure 1~1B
Figure 2~2B
Figure 3
AI summary
An electronic device including: a light guide plate; an imaging unit disposed so as to face the light guide plate and including an image sensor; a plurality of light emitting elements disposed around the imaging unit; and a refractive part interposed at least between the light emitting element and the light guide plate and refracting light emitted from the light emitting element.